samples: drivers: ht16k33: Update sample to remove use of DT_INST
samples: drivers: ht16k33: Update sample to remove use of DT_INST

Simplify sample by removing usage of DT_INST.

Signed-off-by: Benjamin Björnsson <8044ef148b03b50e606a03e6e88e2c21cb9a92a8@gmail.com>

finikorg/zephyr,zephyrproject-rtos/zephyr,finikorg/zephyr,galak/zephyr,galak/zephyr,zephyrproject-rtos/zephyr,galak/zephyr,finikorg/zephyr,finikorg/zephyr,zephyrproject-rtos/zephyr,zephyrproject-rtos/zephyr,galak/zephyr,zephyrproject-rtos/zephyr,finikorg/zephyr,galak/zephyr